[Ultrasonic techniques for removing broken instruments from root canal].

Instruments broken in root canal is one of the frequent complications of endodontic therapy and fortunately, as the rapid development of microscope using in the root canal treatment, most of the broken instruments can be removed with the assistance of ultrasonic appliances. In the present study, we talked about the causes, the removing methods of broken instruments and troubles during the procedures. We put much emphasis on the creation of a straight pathway along the canal as well as some concerns in using the ultrasonic appliances, such as the water spray, the rotating actions and the assistance of microscope, all of which are supposed to offer great benefits for clinically avoiding as well as dealing with broken instruments.